August 22, 2025
2 Min read
Heat and rain can help predict when dengue
A new analysis discovers the seasonal models of dengue, a disease transmitted by mosquitoes, through the Americas, which could help scientists anticipate future epidemics
Dado Galdieri / Bloomberg Creative Photos / Getty Images
Major epidemics of dengue in the Americas tend to occur about five months after an El Niño event – periodic warming of the Pacific Ocean that can disrupt the world weather – has revealed a study. Meanwhile, local epidemics tend to occur about three months after peak summer temperatures and about a month after peak precipitation.
The study, published today in Translational scientific medicinePainted a clearer image of the relationship between the disease transmitted by mosquitoes and climatic conditions in the Americas, a region which saw a record of 13 million cases in 2024.
Dengue is caused by four closely linked viruses and distributed by the Cashier Mosquito species. There is no specific treatment and the disease can cause fever, bone pain and even death.
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Research was based on approximately three decades of surveillance data from 14 countries. The cases of the region tended to increase and lower, on average to six months apart, even in places at 10,000 kilometers.
The results are “useful to anticipate when a region could expect to see an epidemic, which can help to shed light on planning and preparation”, explains Talia Quandelacy, co-author and epidemiologist of the disease of infectious disease at the University of Colorado School of Public Health in Aurora. She notes that, although the link between dengue and the climate is well known, which stands out in the conclusions, is how this association takes place on the whole continent, “especially since it is such a diversified region.”
Grilled mosquitoes
THE Cashier Mosquitoes generally thrive in hot and humid conditions. In addition, the dengue virus incubation period in the mosquito – the time between infection and when the mosquito can transmit the virus – is shortening at high temperatures, the Quandel explains. The virus is replied faster in warmer environments. “There is just a more effective transmission of dengue virus when we have warmer temperatures,” she said.
But the climate is only a factor that stimulates the epidemics of dengue. Immunity by the population and other local conditions are also relevant. For example, mosquitoes are counting on stagnant water to lay their eggs, which is abundant in urban areas that lack suitable sanitation. “The analyzes showing the impact of extreme weather events like El Niño are important but, in particular for arboviruses, we must take into account local characteristics of urban areas,” explains Marcia Castro, specialist in public health at Harvard Th Cha Cha, Boston, Massachusetts. “You have cities without infrastructure, areas such as the growth of slums, then an El Niño comes to exacerbate all the consequences.”
This article is reproduced with permission and was first publication August 20, 2025.
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